Producer Beau Flynn came up with the idea for San Andreas in 1994 when he experienced an earthquake within three weeks of moving to Los Angeles. "The Northridge earthquake hit … and to experience a major earthquake was terrifying, powerful," he says.

Directed by Brad Peyton, the film follows the story of rescue helicopter pilot Ray (Dwayne Johnson) and his wife Emma (Carla Gugino) as they go from Los Angeles to San Francisco to save their only daughter after a magnitude 9-plus earthquake hits the area.

The blend of a massive, destructive calamity and strong personal connections drew Johnson to the story. "I was captivated by the script," he said. "It grabbed me by the throat and didn't let go."

San Andreas has more than 1,300 visual effects shots of roads buckling, bridges snapping and fires erupting across the cityscapes. VFX producer Randall Starr says that almost every individual shot features some special effects - even if it was something as tiny as putting a crack on a wall.

But on top of computer-generated graphics, a lot of the action was shot live. "For a week, I was shooting a boat on a green screen stage, doing all these stunts with water flying around; then it was a helicopter for another week; then a plane. It was pretty wild," says Peyton.

In addition, a 13,000-square foot water tank had to be built. It is currently the largest purpose-built film water tank in Australia, and one of the largest in the world, with its 1.5 million gallon capacity. (Johnson has said only the one used for Titanic is bigger.)

During the shoot, Johnson said he and the cast spent a lot of time with helicopter pilots to try to understand the mechanics of flying a chopper, and finding out "how they look at their job, what they think, and how they're able to separate their emotions from the job," said the former professional wrestler. "Because it's just human nature when something like this happens to go into that fight-or-flight mode. These guys are incredible warriors. Spending time with them was invaluable."

(You know what else is incredible? Johnson broke the Guinness World Record last week for taking the most selfies under three minutes at the film's London premiere. What a fun dude!)

To capture the feeling of disharmony at pivotal scenes, music composer Andrew Lockington said that he "got an old piano and spent two days destroying it with sledge hammers and wire cutters. We had planned to record hitting it with the hammers, and those sounds are blended in with the orchestral elements in the film."

Lockington adds that this deconstructed, bizarre, broken instrument could then play notes in a unique way, and the sounds it created helped to produce an eccentric effect in important parts of the film.

All together San Andreas promises an astonishing story filled with action, heroes, romance and drama. If a film is really as good as its villain, Johnson thinks they're in for the win, because they're up against the greatest foe known to man: Mother Nature.